We used spatial data from previously mapped preferential groundwater discharges throughout the Farmington River watershed in Connecticut and Massachusetts (https://doi.org/10.5066/P915E8JY) to guide water sample collection at known locations of groundwater discharging to surface water. In 2017 and 2019 - 2021, samples were collected during general river baseflow conditions (July ? November, less than 30.9 cms mean daily discharge (USGS gage 01189995, statistics 2010-2022) when the riverbank discharge points were exposed. We collected a suite of dissolved constituents and stable isotopes of water directly in the shallow saturated sediments of active points of discharge, and coincident stream chemical samples were also collected adjacent to locations of groundwater discharge. Data collected includes nutrients (NO3, NH4, Cl, SO4, PO4, dissolved organic carbon (DOC), and total nitrogen (TN)), greenhouse gases (CO2, CH4, and N2O), dissolved gases (N2, dissolved oxygen (DO)), conductivity, sediment characteristics, temperature, and spatial information. This dataset includes 2 main files: 1) Farmington_Chemistry_2017_2021.csv contains attribute information for each biogeochemical constituent collected at preferential groundwater discharges along the Farmington River network. 2)Farmington_Temporal_Cl_Rn_Iso_2020.csv contain attribute information for source characteristic data (Chloride, Radon, Isotope) collected at locations of repeat sampling at 5 groundwater seep faces along the Farmington River (Alsop and Rainbow Island).
more »
« less
Thermal infrared images of groundwater discharge zones in the Farmington and Housatonic River watersheds (Connecticut and Massachusetts, 2019)
Locations of groundwater discharging to surface water are hydrologically and ecologically important for nutrient processing and thermal refugia, yet little is known about the spatial distribution of groundwater discharges at the river network scale. Groundwater discharge locations can be used to identify anomalous groundwater discharging to surface water as colder groundwater interfaces with warmer surface water in late summer. This data release contains GPS locations, thermal infrared images, and direct temperature measurements of groundwater discharges throughout the Farmington and Housatonic River watersheds. These data were collected in late summer/ early fall 2019 to characterize the spatial distribution of groundwater discharges throughout the Farmington and Housatonic River networks. The initial data release contains groundwater discharge locations and associated thermal images along the Salmon Brook River in the Farmington River watershed. Additional data for the Farmington and Housatonic River watersheds will be added to this dataset in the future. This dataset contains 3 files: 1) SalmonBrook_FLIR.zip is a zipped directory containing thermal infrared and real color images. 2) SalmonBrook_Image_Details.csv contains attribute information for each thermal image. 3) SalmonBrook_Seeps.shp is an ESRI shapefile of the groundwater discharge locations with FLIR thermal images and field notes. Files associated with this shapefile include: the database file SalmonBrook_Seeps.dbf, the projection file SalmonBrook_Seeps.prj, and the geodatabse file SalmonBrook_Seeps.shx. 4) LegacyN_FLIR_2019_readme is a high level readme text file that describes all of the files on the root landing page.
more »
« less
- Award ID(s):
- 1824820
- NSF-PAR ID:
- 10354591
- Publisher / Repository:
- U.S. Geological Survey
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Using the horizontal-to-vertical spectral-ratio (HVSR) method, we infer regolith thickness (i.e., depth to bedrock) throughout the Farmington River Watershed, CT, USA. Between Nov. 2019 and Nov. 2020, MOHO Tromino Model TEP-3C (MOHO, S.R.L.) three-component seismometers collected passive seismic recordings along the Farmington River and the upstream West Branch of Salmon Brook. From these recordings, we derived resonance frequencies using the GRILLA software (MOHO, S.R.L.), and then inferred potential regolith thicknesses based on likely shear wave velocities, Vs, intrinsic to the underlying sediment. Three potential shear wave velocities (Vs = 300m/s, 337m/s, 362 m/s) were considered for Farmington River watershed sediments, providing a range of potential depth estimates along the Farmington. This release contains raw passive seismic recording data, processed resonance frequency data, and the resulting inferred depth estimates displayed in both tabular and vector form. This dataset currently contains 3 zipped files: 1) ?Processed.zip? is a zipped directory containing .asc text files of processed passive seismic data, individual processed reports, tabulated results, and an associated summary text file, 'readme_Processed.txt'; 2) 'Raw.zip' contains .saf text files of passive seismic recordings and an associated 'readme_Raw.txt;' and 3) ?XYLegacyN_HVSR.zip'? contains ESRI shapefile of HVSR point locations with attribute data & a map image offering a visualization of the depth results (where, Vs = 300m/s). Additionally, the main folder contains LegacyN_HVSR_readme.txt which describes these sub-directories in further detail.more » « less
-
Groundwater discharge to rivers takes many forms, including preferential groundwater discharge points (PDPs) along riverbanks that are exposed at low flows, with multi-scale impacts on aquatic habitat and water quality. The physical controls on the spatial distribution of PDPs along riverbanks are not well-defined, rendering their prediction and representation in models challenging. To investigate the local riverbank sediment controls on PDP occurrence, we tested drone-based and handheld thermal infrared to efficiently map PDP locations along two mainstem rivers. Early in the study, we found drone imaging was better suited to locating tributary and stormwater inflows, which created relatively large water surface thermal anomalies in winter, compared to PDPs that often occurred at the sub-meter scale and beneath riparian tree canopy. Therefore, we primarily used handheld thermal infrared imaging from watercraft to map PDPs and larger seepage faces along 12-km of the fifth-order Housatonic River in Massachusetts, USA and 26-km of the Farmington River in Connecticut, USA. Overall, we mapped 31 riverbank PDPs along the Housatonic reach that meanders through lower permeability soils, and 104 PDPs along the Farmington reach that cuts through sandier sediments. Riverbank soil parameters extracted at PDP locations from the Soil Survey Geographic (SSURGO) database did not differ substantially from average bank soils along either reach, although the Farmington riverbank soils were on average 5× more permeable than Housatonic riverbank soils, likely contributing to the higher observed prevalence of PDPs. Dissolved oxygen measured in discharge water at these same PDPs varied widely, but showed no relation to measured sand, clay, or organic matter content in surficial soils indicating a lack of substantial near-surface aerobic reaction. The PDP locations were investigated for the presence of secondary bank structures, and commonly co-occurred with riparian tree root masses indicating the importance of localized physical controls on the spatial distribution of riverbank PDPs.more » « less
-
more » « less
Abstract Groundwater discharge to streams is a nonpoint source of nitrogen (N) that confounds N mitigation efforts and represents a significant portion of the annual N loading to watersheds. However, we lack an understanding of where and how much groundwater N enters streams and watersheds. Nitrogen concentrations at the end of groundwater flowpaths are the culmination of biogeochemical and physical processes from the contributing land area where groundwater recharges, within the aquifer system, and in the near-stream riparian area where groundwater discharges to streams. Our research objectives were to quantify the spatial distribution of N concentrations at groundwater discharges throughout a mixed land-use watershed and to evaluate how relationships among contributing and riparian land cover, modeled aquifer characteristics, and groundwater discharge biogeochemistry explain the spatial variation in groundwater discharge N concentrations. We accomplished this by integrating high-resolution thermal infrared surveys to locate groundwater discharge, biogeochemical sampling of groundwater, and a particle tracking model that links groundwater discharge locations to their contributing area land cover. Groundwater N loading from groundwater discharges within the watershed varied substantially between and within streambank groundwater discharge features. Groundwater nitrate concentrations were spatially heterogeneous ranging from below 0.03–11.45 mg-N/L, varying up to 20-fold within meters. When combined with the particle tracking model results and land cover metrics, we found that groundwater discharge nitrate concentrations were best predicted by a linear mixed-effect model that explained over 60% of the variation in nitrate concentrations, including aquifer chemistry (dissolved oxygen, Cl−, SO42−), riparian area forested land cover, and modeled physical aquifer characteristics (discharge, Euclidean distance). Our work highlights the significant spatial variability in groundwater discharge nitrate concentrations within mixed land-use watersheds and the need to understand groundwater N processing across the many spatiotemporal scales within groundwater cycling.
-
As the climate warms and dry periods become more extreme, shallow groundwater discharge is generally becoming a less reliable source of streamflow while deep groundwater discharge remains a more resilient source. The implications of shifts in the relative balance of shallow and deep groundwater discharge sources are profound in gaining streams. These different sources exert critical controls on stream temperature and water quality as influenced by legacy groundwater contaminant transport. Groundwater discharge flux rates over time were used for the inference of source groundwater characteristics to prominent riverbank groundwater discharge faces along the mainstem Farmington River, CT USA. To estimate groundwater discharge rates, we deployed sediment temperature loggers (iButton #DS1922L, Maxim Integrated, Inc., San Jose, CA, USA) in vertical profilers installed directly into mapped preferential groundwater discharge points across extensive riverbank discharge face features.Temperature data contained in this release were collected from June 24 to November 5, 2020, at 40 distinct discharge point riverbank locations, similar to those described by Barclay et al. (2022) and Briggs et al. (2022). Saturated sediment thermal conductivity and heat capacity were measured in-situ with a TEMPOS Thermal Property Analyzer (TEMPOS, Meter Group, Inc., Pullman, WA, USA) at multiple points across each riverbank discharge face to aid in estimating groundwater discharge flux rates. Barclay, J. R., Briggs, M. A., Moore, E. M., Starn, J. J., Hanson, A. E. H., & Helton, A. M. (2022). Where groundwater seeps: Evaluating modeled groundwater discharge patterns with thermal infrared surveys at the river-network scale. Advances in Water Resources, 160. https://doi.org/10.1016/j.advwatres.2021.104108 Briggs, M. A., Jackson, K. E., Liu, F., Moore, E. M., Bisson, A., & Helton, A. M. (2022). Exploring Local Riverbank Sediment Controls on the Occurrence of Preferential Groundwater Discharge Points. Water, 14(1). https://doi.org/10.3390/w14010011more » « less
